Fixed Assets and Asset Retirement Obligations - (Forecast of Accretion Expense) (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Forecast of Future Accretion Expense [Abstract]
2018	$ 10,799
2019	9,760
2020	9,429
2021	10,069
2022	$ 10,753

Asset Retirement Obligation, Future Payments Due In Four Years

No definition available.

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due In Three Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueInThreeYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due In Two Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueInTwoYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due, Next Twelve Months

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueNextTwelveMonths
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Asset Retirement Obligation, Future Payments Due in Five Years

No definition available.

Name:	gel_AssetRetirementObligationFuturePaymentsDueinFiveYears
Namespace Prefix:	gel_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Forecast of Future Accretion Expense [Abstract]

No definition available.

Name:	gel_ForecastofFutureAccretionExpenseAbstract
Namespace Prefix:	gel_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration